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Dynamics

DYNAMICS

Dynamics is the number one issue in skiing

Nothing is more important in technique yet it is the one subject that is completely misunderstood throughout the entire ski industry and is incorrectly taught from day one.

Professional Error

Professional ski instructors the world over are dominated by national systems and those systems share information internationally through a body called "Interski". Shared information would be fine but in reality this turns out to be a shared conformity and consensus that has no basis in either intelligence or common sense. In all national systems one of the main areas that an instructor is assessed on during his training and examinations is "Balance". The explanations of "Balance" are all pretty much the same - wrong! When confronted with this the standard excuse is "it's only semantics" and "we are saying the same thing but just using different words" or "we have to use a vocabulary the public understand" or even just total denial: " I teach the same thing as you!". This is false and shows a truly profound lack of understanding. I even had one extremely misguided CEO of BASI in the UK tell me that Newton's second law couldn't be used in ski teaching. Just watch!

I have put two articles on this blog explaining the source of the confusion over the issue...

How does this work?

It works the same way that a bicycle works. On the bike it's the Centre of Mass falling to one side (or the other) that controls both the ability to stay upright and the ability to turn. Both cycling and skiing need some forward speed to work - not a lot but enough for the equipment to activate a certain process. When moving forward and you fall over to one side the bike (or ski) changes shape. The handlebars move or the ski bends. The bike then cuts in front of the path (straight line trajectory) of your body and forces you back up. This generates a constant feedback process, creating a "feedback driven disequilibrium system". DIS-equilibrium is what is happening - not "equilibrium" (balance). This means is that if you lose consciousness the process stops and you collapse in a useless heap on the ground - only then finding yourself really in balance. Any object that uses balance is either asleep or inanimate - like a building for example.

Another name for disequilibrium is "acceleration". In physics there are two branches of mechanics - Statics and Dynamics. Statics deals with inert objects like buildings and dynamics deals with accelerating objects like skiers.

To exploit this dynamic system correctly in skiing you need to be very aware of it because unlike with the bicycle the upper limits of dynamics are the defining characteristic in performance. On a bicycle you want to stay mainly very upright and just focus on pedalling. In skiing you are focused on "falling over" (which creates turning) - the propulsion is already there from gravity and control of speed is from turning. The fundamental difference is that rubber quickly reaches its limits and the tyres skid away from beneath you. In skiing the more you actively incline the harder the skis bite and the harder it becomes to incline more as the skis fight back to bring you up. The skier's level is defined by the limit of dynamic range that the skier can generate. The better the skier the bigger the dynamic range possible.

Letting Go

When developing dynamics it is best to simply follow the skis around the turn - just like you would do on a bicycle. This removes any possible confusion from upper/lower body separation (facing downhill etc). The skier has to have some forward speed either across the hill or downhill and then topple to one side or the other - in the direction of the desired turn. This might sound easy to achieve but it can be confusing for several reasons. Most people are much more protective than they imagine and really do hold onto the emotional security of static "balance". Letting go and really trying to fall over is a completely different mindset. The appropriate actions are also the opposite of what many trained skiers believe or have trained into their body and brain as unconscious skills. It's still possible to actually fall and hit the ground if the process isn't carried out correctly - but when that happens it's always lack of coordinated dynamics that's the problem - not the dynamics. Sometimes it's because the support base (legs, posture etc) is very poor and sometimes it's due to parasitic or unconscious movements or incorrect timing.

Big Biking

The falling over or "toppling" to one side or another generates a down/up motion the same as a motorbike going down into a turn and then coming back up out of it. Initially, on skis, it's best to use the entire body toppling (inclination) into a turn and to avoid trying to create any angulation. Later on hip angulation can be introduced appropriately and with a proper sense of movement - but just dropping the hips into the turn is never appropriate. At this point people start to do all sorts of weird things like lobbing their heads only into the turn, sometimes with the shoulders. They do everything possible to actually avoid moving the Centre of Mass into this seemingly scary and unpredictable space. Oddly, it's only when they see themselves on video that they know they are doing it - even if they have been verbally told about it many times.

Gravity

Falling over due to gravity is an acceleration. This acceleration is generally enough to get the whole system working. This is the tricky part though because the more you accelerate due to gravity the less pressure is on the ski - because some of the gravity that was causing pressure is now being used to accelerate you. This presents no problems on a smoothly groomed piste but it does generate problems in more difficult conditions. With enough forward speed the sidecut of the ski coming onto its edge will generate pressure as the ski cuts in front of your trajectory. This pressure is the result of a force that is trying to lift you up - generated by the ski. If you don't have any speed this won't work. We all know that it's extremely hard to remain upright on a bicycle at very low speeds.

Many people can manage to get skiing to function at this basic level completely unconsciously - just like they do on a bicycle. Some people fail badly however at this stage because teaching systems tell them to "lean outwards" to get their weight on the outside leg. Of course this sends the Centre of Mass totally in the wrong direction with desperate consequences for many people who apply this instruction accurately. If the learning is done using slalom poles instead of instruction then the correct unconscious movements can still be cultivated - due to the physical requirement to move towards the poles. This is how the foolish and destructive Darwinian process of developing a racing ski team begins - starting with 10,000 children (USA) to produce a successful team of 8. I'm all for competition - but not using Natural Selection as the main criterion - "nurture" is far more important - especially for children. I'd rather see 9992 succeed very well and 8 fail than the other way round.

In the first part of the turn gravity adds to speed and so lets the ski build up pressure this way despite the partial loss of pressure from falling.

In the second part of the turn gravity directly builds up pressure, increased ski edge angle increases the power (pressure) of the ski and deceleration of the body also increases the pressure.

Learning to initiate a turn just by moving the body slightly in the direction of he turn is very easy to do. The problem however is that people are surprised by the acceleration and tend to head straight off down the mountain. Young children as especially prone to bombing off straight downhill with no control over speed. Unless there is a conscious effort to strongly move into the turn then when the forces build up, lifting the skier up and therefore out of the turn, the unprepared and surprised skier just cannot cope.

(The simplest way to learn to overcome this automatically to some extent is to lift the new inside ski but lower level skiers are not usually able to stand comfortably on one ski.)

The Magic Wall

The best way I have found to introduce dynamics to people who can already ski is through some simple static exercises on the hill.

The first practical exercise is where I stand beside the skier, both facing the same way across the hill. The skier then leans against me shoulder to shoulder in a posture similar to trying to stop somebody from pushing open a door. The harder the skier pushes the greater the force on the foot furthest from me. The small amount of inclination is already enough for the ski edge to bite into the snow and grip. I then move about a foot away and ask the skier to stand up and move across very slowly to bridge the small gap between us - to come shoulder to shoulder once again. This slow movement causes all the pressure to shift onto the other ski instead until the support is established against my shoulder. Then I ask the skier to repeat this rapidly with an acceleration. If a good acceleration is used the pressure is instantly on the furthest foot and remains there. Even using gravity to fall against me will fail to make this happen because the acceleration of toppling is so slow to start with. Lifting the foot closest to me will place all the pressure on the furthest ski also but it won't necessarily put the ski on edge. The only thing that gives both pressure and edge is a strong impulse to push hard against my shoulder. This involves a slight downsink to get strongly positioned despite the push with the legs. The purpose of all of this is to feel what the body needs to do to start a turn using dynamics. When actually skiing this is the motion required and the feeling at the feet is what needs to be recognised - because that is the only place where force or pressure is felt directly. This feedback must however be linked to the deliberate movement of the Centre of Mass.

There is obviously no pressure against the shoulder when skiing and this is where the magic of Newton's second law comes in. The force against the shoulder is replaced by acceleration. Force is equivalent to mass being accelerated - that is the 2nd law of motion. I explain this to children by describing it as an invisible magic wall which you can't see or feel but the harder you push against it the better it supports you. All you need is to believe in the magic. This applies not only at the start of the turn but you must push even harder inwards as the turn progresses.

We begin to use this simply from a shallow traverse across the hill to swing uphill and stop. The traverse is progressively taken steeper to the fall-line and eventually crossing it and into full turns, but keeping them shallow to avoid complications.

Very short carving skis are ideal for exploring the limits of dynamics without the need for a great deal of speed. A ski with release bindings and about 5m turn radius is ideal.

Entering this magical universe of accelerations is extremely liberating. There is a powerful sense of freedom and the harder you try to fall the more secure you become. This can be a bit of a shock to people who have previously been locked into the false "balance" paradigm and given instruction based upon statics.

Improving in skiing from here on in is largely an issue of developing dynamics, extending the dynamic range and exploring many adaptations to terrain and snow. Initially people can only normally manage about 15 degrees of motion to each side. This can be extended to almost 90 degrees.

Turn Exit Dynamics

The second phase of development involves the turn completion. There is a complication involved due to the mountain not being flat. Where exactly is the end of the turn? Most people automatically assume that it's when they are vertical and moving across the hill. For "dynamic" skiing that is not correct. The skier has still not completed the turn. The turn is only over when the skier is crossing the hill with the skis flat and the body momentarily perpendicular to the hill. This can naturally only be sustained very briefly and is part of a dynamic process. The turn completion is every bit as important as the turn initiation.